Manufacture of goods containing rubber or similar materials



Patented Mar. 5, 1935 r UNITED STATES OFFICE MANUFACTURE OF GOODS CONTAINING RUBBER OR SIMILAR, MATERIALS Edward Arthur Murphy and Evelyn 'WiIliam V Madge, Wylde Green, Birmingham, England, assignors to Dunlap Rubber Company Limited, London, England, a British company- No Drawing. Application March 16,1933,-Serial I No. 661,191. I Great BritainflMarch 24, 1932 if 8 Claims. (Cl'. 18- 53) This invention comprises improvements in or mesh wire gauze. If desired, suction maybe relating to .the manufacture of goods containing employed to aid filtration and/or pressure may be; rubber or similar materials from aqueous emul-V applied to the filter cake. a sions or, dispersions of the kinds hereinafter Aftern large proportion of thefwaterlhas been,

specified. a I l V remored,..acompaotsheetis obtained which may 5 The object of the invention is to. produce pobesremoved 'andwmoulded in wet, condition and rous or micro-porous articles of hard vulcanized thereafter vulcanizediundersuch conditions that rubber or the like in admixture with fibrous maevaporation: .of the liquid :contai-ned thereinris terials. prevented. The vulcanized product is then dried;

10* According tolthe invention the. process for the Examples .of suitable coagulants are acetic 10 q manufacture of porous or micro-porous goods of acid, iormic ,acid, mydrochloriczacid, sulphuric hard vulcanized rubberor the like in admixture acid, sodium silico-fiuoride, aluminum chloridawith fibrous materials comprises admixing fibrous alum; barium chloride, calcium nitratal zinc material with fiocculent or granular precipitates .sulphate, magnesium acetate, magnesium ,sulproduced from aqueous dispersions of the kinds phate, ferrousasulphate, and ferric sulphate. l5 hereinafter specified, effecting compacting of the Examples.ofsubstanceshaving.arestraining eiaforesaid admixture of flocculent or granular fecton the coagulationare caustic potash,.casein, precipitates and fibrous materials .by a filtering sodium .aluminate,.. glue and gum. acacia. Theoperation and thereafter vulcanizing in known, mount 01.511011 substances usedxalso influences 5O manner the products soobtained under suchconthedegreeoi subdivision .of the granular disperg ditions that evaporation of the liquid contained sion. M i a I v thereinis prevented. V The degree of concentration hasalso an influ- The filtering operation may be carried out in, ence, on the fineness of the precipitate. 1 In genconjunction with an operation such as moulding,- eral, the lower the concentration, the finer the spreading, impregnating or .dipping. If desired, initial precipitate. I p

the filtration in the first place need only be .car- The aqueous dispersions aforesaid are preferried out-to produce a thick aqueous paste .conab y p y d at; Such dilutions that 100 ccs. taining the fiocculent or granular precipitate and hereofcontain :not,m0rethan l0% Oftotal Solidsfibrous material, which paste can be thereafter By the suitable choice of reagents andcondispread upon, for instance, coarse orfine fabrics. 15 o W granular dispersions of va In the case of coarse fabric, the meshes become ins t n y.-Can'lbe formed. 7. closed 'by granular precipitates. Porous moulds If desired, the ,granular precipitates can be can be used, for example, topproduce cylindrical Washed fre from,-,solub1ereactionproducts, uch articles of micro-porous rubber by dipping. as soluble.sulphatesorrchlorides,,by-known -means It has been known for some time that instead aaior instance, by decantation or filtration and 35 of the usual adherent coagulum, it is possible Washing prior to their compacting. to obtainrubber as a flocculent precipitate from The emulsions or dispersions of rubber or the latex by the use of certain coagulants' and by like may containin addition to rubber, guttaadjustment of the; concentration of the latex Durcha, blalata, or similar vegetable resins :occur- 40 as described, for instance, in Estate Rubber, ring na a y r fi a y. c artific al O. de Vries, page 143, 1920. I V aqu us dispersions may include those of coagu- The aforesaid flocculent orgranular precipi-- lated ru b r, vulcaniz d r b e Sy h Tube tates can be prepared from rubber latex in conwaste-or reclaim. trollable manner by the use of varied coagulatfmy o the aforesaid dispersions may, contain ingagents andmethods of coagulation providedthe usual known compounding and vulcanizing in- 45 that the coagulation is effected in the :presence gredients and/or may :be in the first instance in V of arelatively large quantity of water, and with; concentrated form, 7 I or without the presence of-certain amounts of, It is desirable that the proportion of vulcaniz alkaline or colloidal substances found to have a ing ingredient should be high. restraining effect upon thejcoagulationr I Concentrates such as are obtained in Patent The fibrous materials may consist of mineral 1,846,164, Feb. 23, 1932, or in British Patent 219,- and/or vegetable fibres such as asbestos 635, to which may beadded any one or more of and/or cellulose fibres. the usual known compoundingingredients, may Y The filtering means employed may be, for exalsobe employed subsequent to dilution. a ample, .of ceramic material, cotton fabric, or fine The aforesaid vulcanization and/or compoundtated by treating the filter cake obtained with a rubber solvent as, for instance, carbon tetrachloride, which may be mixed with a mutual solvent for water and the rubber solvent employed, as for example, alcohol.

In carrying out the process-of the present invention, it has been ,found that the presence of asbestos in most cases makes it unnecessary to,

employ means for maintaining the wet coherent mass during vulcanization in a distended condition. v

For instance, according to the present inven-' ti'on', it has been found to be usually unnecessary to place the wet coherent mass between plates having, 'for instance, embossed patterns-on their surface, or between layers of fabric material so as to prevent any shrinkage of the wet coherent mass during the vulcanization. r r The following example illustrates how the process can be eifected for the productionof microporous filters.

tions:

V a Parts by weight Rubber '100 Sulphur 40 Zinc oleate -3 l /lercaptobenzthiazole 0. 5 Mineral oil China clay 10 Zinc oxide r 2 in Patentsl,846,164 and 1,898,604.

The final solid content of the mixing is 53%. I

This mixing is converted into a granular precipitate in the following manner To 280 parts by weight of the mixing 1.8 parts by weight of 25% solution of caustic soda, 9 parts by weight of a 10% solution of casein, 1150 parts by weight of water are added. To this diluted mixing 11 parts by weightof sodium silicate (50% concentration) in the form of a 10% solution, 11 parts by weight of magnesium sulphate crystals in the formof a 10% solution are added; the mixture being well stirred after each of the additions. 7 r 7 7:

The dispersion of asbestos is prepared by agitating 150 parts byweight ofasbes tos fibre with 2850 parts by weight of water, by any suitable means, as for instance, by the use of a beating engine.

The rubber precipitate is: then added to the asbestos pulp, and the agitation continued for a short period. The flocculent or granular precipitate of rubber and asbestos is'poured onto a suitably constructed filter so as to give filter cakes of the desired dimensions and patterns for immediate vulcanization with or without the removal of the filter cakes from the press.

It may be desirable to remove excess of water from the sheets by passing them through rolls.

7 dry. 1

The porous ebonite filters produced according to'this example have been found to have a high degree of porosity and to have good flexibility.

Having now'particularly described our invention, what we claim is- 1. A process for'the manufacture of porous or micro-porous goods of vulcanized rubber in admixture with fibrous materials which comprises mixing fibrous materials with flocculent or granular precipitates in aqueous suspension produced from aqueous dispersions of rubber material, filtering the aforesaid mixture of flocculent or granular precipitates and fibrous'materials to a compact mass and vulcanizing the products so obtained while preventing evaporation of the liquid contained therein. a

removed from the mixture by a filtering operation the compact sheet obtained is removed from r the filter and moulded in wet condition and A latex mixing having the following composithereafter vulcanized under such conditions that evaporation of the liquid contained therein is prevented.

3. A process for the manufacture of porous or micro-porous goods of vulcanized rubber in admixture with fibrous materials which comprises mixing fibrous materials with flocculent or granular precipitates in aqueous suspension produced from aqueous dispersions of rubber material, separating the aforesaid mixture of precipitates of fibrous materials in a compact mass from the dispersingliquid and thereafter vulcanizing the separated material while preventing evaporation of the liquid contained therein.

4. The process of claim 3, in which the separated mass is moulded in wet condition before vulcanization.

5. The process of claim 1 in which excess of water is removed from the filtered material by passing it in sheet forth between rolls.

6. The process of claim 1 in which said flocculent precipitates are produced with simultaneous precipitation of a silicate. a

7. The process of claim 1 in which said flocculent precipitates are produced with simultaneous precipitation of magnesium silicate.

8. A process for the manufacture of porous or microporous goods of vulcanized rubber in admixture with fibrous materials which comprises adding to an aqueous dispersion of rubber material containing an alkali silicate in solution, a magnesium salt having ions that coagulate the dispersion to produce flocculent or granular precipitates as compounded rubber containing magnesium silicate, mixing said precipitates with fibrous materials, filtering the resulting mixture of precipitates and fibrous materials to a compact mass, and vulcanizing the product so obtained while preventing evaporation of the liquid contained therein.

EDWARD ARTHUR MURPHY. EVELYN WILLIAM. MADGE. 

